1. Field of the Invention
The present invention relates to optical receivers. More particularly, this invention pertains to an interconnection between an optical waveguide and an optical receiver.
2. Description of Prior Art
Optical receivers, such as those employed in fiber optic systems, are generally encapsulated within cylindrical metal casings. The light-sensitive converter face is located at the smallest possible distance behind a glass window in the top of the metal casing. In the simplest case, the end of the optical waveguide is fitted in a butt-jointed fashion onto the window face of the detector casing and bonded thereto. In more complex structures, provision is made to guide the optical waveguide into the interior of the detector casing. The bushing of the casing must be sealed by a technically-relatively difficult bonding or soldering technique.
FIG. 2 is a side sectional view of such an optical waveguide connection in accordance with the prior art. A planar, light-sensitive converter 4 is located behind a translucent window 5 in an encapsulation 1 having electrical terminals 2 and 3. The end of the optical waveguide 6 is attached in front of the window 5 by means of a bonding agent 7.
In many fiber optic systems, the light radiation guided in optical waveguides must be fed to the optoelectric converter with as little loss as possible to permit evaluation of information coded onto the light. In such cases, a stable connection must be provided between the optical waveguide and the receiver. The coupling between the optical waveguide and the receiver (i.e. the converter) should not change (or change as little as possible) in response to varying environmental influences.
Simple bonding of the optical waveguide 6 to the glass window 5 of the detector encapsulation 1 (as explained with reference to FIG. 2) experiences inadequate stability. When the flexible optical waveguide 6 is bent, the connection is easily damaged. Alignment of light emerging from the optical waveguide accompanied by bending can change in such a way that part of the light intensity no longer strikes the light-sensitive surface of the converter 4. On the other hand, an embodiment with a casing bushing requires a special component structure comprising converter and casing. In many cases, standard detectors cannot be used in cylindrical casings with a glass window.